1. Field of the Invention
The present invention relates to a rear projection apparatus which is provided with at least two optical projection means and means for preventing defects due to a blocking plate provided between screen components for preventing the overlap of the adjacent projected images along joint portion between the rear projection type screen components.
2. Description of the Prior Art
As shown in Japanese Utility Model Unexamined Publication No. 62-6733, a means for preventing a reflection of the projected light has not been provided on a blocking plate between the adjacent projected images.
For this reason, if a distance between the adjacent images is short, the projected light is reflected by the blocking plate to be introduced into the screen, so that a peripheral portion of the blocking plate is brightened to degrade the contrast.
According to the blocking plate disclosed in Japanese Utility Model Unexamined Publication No. 62-6733, a ray of light projected so that a pupil of a lens is brightened due to scattering light is overlapped with the directly projected light. As a result, a black level on the screen is remarkably floated up so that the contrast or the image quality is degraded.
This will be explained with reference to FIGS. 11 and 12 showing general projection means. In such projection means, a ray of overlapping light, such as scattering light of the image, projected on a blocking plate 5 projected at a joint portion between the images is reflected at a surface of the blocking plate 5, so that the reflection light 8 causes shades 9 with a width W on both sides of the joint portion as shown in front view in FIG. 12, thus making the black level on the screen float up to considerably reduce the contrast or the image quality. Also, in order to avoid the shade, it is necessary to provide a wide (thick) frame to cover the width W.
Also, if the frame is provided to the screen, the projected light is blocked by the frame. Thus, it is impossible to project the image on a portion, corresponding to the blocking plate, of the screen.